1. University of Freiburg

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    1. Mentioned In 18 Articles

    2. Characterisation of vascular changes in different stages of Stargardt disease using double swept-source optical coherence tomography angiography

      Characterisation of vascular changes in different stages of Stargardt disease using double swept-source optical coherence tomography angiography
      Objective To describe vascular changes in different stages of Stargardt disease (STGD) via double swept-source optical coherence tomography angiography. Methods and analysis Prospective, cross-sectional casecontrol study. Twenty-three patients (45 eyes) with ABCA4 mutations graded according to the Fishman STGD classification and 23 controls (23 eyes) were included. Two independent investigators quantified the foveal avascular zone (FAZ) in the superficial and deep capillary plexus (SCP/DCP) and the areas presenting rarefied ...
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    3. Reduction of periodic noise in Fourier domain optical coherence tomography images by frequency domain filtering

      Reduction of periodic noise in Fourier domain optical coherence tomography images by frequency domain filtering
      In Fourier domain optical coherence tomography (FDOCT) coherence noise is caused by interference of light waves back-reflected or scattered from different spots within a measuring depth or from optical components within the OCT system such as a bended optical fibre. This coherence noise appears as periodic stripe patterns along the axial direction in resulting images. Background subtraction and physical segmentation are used to degrade the periodic coherence noise in previous ...
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    4. Value of Optical Coherence Tomography Angiography Imaging in Diagnosis and Treatment of Hemangioblastomas in von Hippel-Lindau Disease

      Value of Optical Coherence Tomography Angiography Imaging in Diagnosis and Treatment of Hemangioblastomas in von Hippel-Lindau Disease
      BACKGROUND AND OBJECTIVE: The introduction of optical coherence tomography angiography (OCTA) provides new insights into the retinal vasculature. The aim of this study was to explore the value of OCTA in imaging retinal hemangioblastomas and monitoring laser treatment in patients with von Hippel-Lindau (VHL) disease. PATIENTS AND METHODS: Ten eyes of 10 patients with VHL disease were included in this retrospective case series. All patients underwent complete ophthalmological work-up including ...
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    5. Quasi-Bessel beams from asymmetric and astigmatic illumination sources

      Quasi-Bessel beams from asymmetric and astigmatic illumination sources
      We study the spatial intensity distribution and the self-reconstruction of quasi-Bessel beams produced from refractive axicon lenses with edge emitting laser diodes as asymmetric and astigmatic illumination sources. Comparing these to a symmetric mono-mode fiber source, we find that the asymmetry results in a transition of a quasi-Bessel beam into a bow-tie shaped pattern and eventually to a line shaped profile at a larger distance along the optical axis. Furthermore ...
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    6. The APOSTEL recommendations for reporting quantitative optical coherence tomography studies

      The APOSTEL recommendations for reporting quantitative optical coherence tomography studies
      Objective: To develop consensus recommendations for reporting of quantitative optical coherence tomography (OCT) study results. Methods: A panel of experienced OCT researchers (including 11 neurologists, 2 ophthalmologists, and 2 neuroscientists) discussed requirements for performing and reporting quantitative analyses of retinal morphology and developed a list of initial recommendations based on experience and previous studies. The list of recommendations was subsequently revised during several meetings of the coordinating group. Results: We ...
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    7. Bimodal endoscopic probe combining white-light microscopy and optical coherence tomography

      Bimodal endoscopic probe combining white-light microscopy and optical coherence tomography
      We present a novel bimodal endoscopic imaging probe that can simultaneously provide full-field white-light video microscopy and confocal optical coherence tomography (OCT) depth scans. The two modalities rely on spectrally separated optical paths that run partially in parallel through a micro-optical bench system, which has a cross-section of only 2 mm 2.76 mm and is realized via standard silicon micromachining techniques. With a numerical aperture of 0.061, the ...
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    8. Coronal in vivo forward-imaging of rat brain morphology with an ultra-small optical coherence tomography fiber probe

      Coronal in vivo forward-imaging of rat brain morphology with an ultra-small optical coherence tomography fiber probe
      A well-established navigation method is one of the key conditions for successful brain surgery: it should be accurate, safe and online operable. Recent research shows that optical coherence tomography (OCT) is a potential solution for this application by providing a high resolution and small probe dimension. In this study a fiber-based spectral-domain OCT system utilizing a super-luminescent-diode with the center wavelength of 840 nm providing 14.5 m axial resolution ...
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    9. A Tunable Optofluidic Silicon Optical Bench

      A Tunable Optofluidic Silicon Optical Bench
      A miniaturized optical bench, based on silicon micromachining and with high modularity and flexibility, is presented. This optical microsystem integrates optics, fluidics, high-precision mechanics, and focal length tunable lenses and allows the realization of numerous optical arrangements, such as telephoto and retrofocus systems. Due to its dimensions, the technology may be used for designing a variety of endoscopic imaging probes, including those for optical coherence tomography. As the measuring beam ...
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    10. Highly compact imaging using Bessel beams generated by ultraminiaturized multi-micro-axicon systems

      Highly compact imaging using Bessel beams generated by ultraminiaturized multi-micro-axicon systems
      Employing Bessel beams in imaging takes advantage of their self-reconstructing properties to achieve small focal points while maintaining a large depth of focus. Bessel beams are efficiently generated using axicons, and their utility in scanning imaging systems, such as optical coherence tomography (OCT), has been demonstrated. As these systems are miniaturized to allow, for example, endoscopic implementations, micro-axicons are required to assure the maintenance of a large depth of focus ...
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    11. Scanning and Tunable Micro-Optics for Endoscopic Optical Coherence Tomography

      Scanning and Tunable Micro-Optics for Endoscopic Optical Coherence Tomography
      The design, fabrication, and integration of micro-optical components for beam focus and steering are demonstrated in an endoscopic optical coherence tomography (OCT) system. The relevant components, a membrane-based microfluidic tunable microlens and an electrostatic 2-D scanning micromirror, are fabricated using silicon and polymer-based microelectromechanical system technologies. All components are assembled inside a 4.5 $muhbox{m}$ diameter probe. The design of the optical system, including substantiation of the need for ...
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    12. Integrated three-dimensional scanner for endoscopic optical coherence tomography

      Integrated three-dimensional scanner for endoscopic optical coherence tomography
      Numerous optical imaging techniques have been developed for clinical diagnostics; among these, optical coherence tomography (OCT) has proven to be of considerable utility due to its ability to non-destructively image below the surface of tissue. Endoscopic OCT systems will further extend the capabilities of this approach but require an additional means for scanning in two or three dimensions. We present an integrated optical microsystem which allows scanning of an optical ...
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    13. OCT imaging with high lateral resolution using a dynamically focusing multi-lens system

      This article studies the combination of the time-domain OCT modality with a dynamically-focusing micro- lens-system. Combining the tunable lens with a fix-focal lens in the sample arm of the OCT setup shows a considerable improvement on the OCT image quality, mainly, the lateral resolution and the signal-to-noise ratio. We present an experimental method and the related first measurements of the lateral resolution of the OCT system using the tunable lens ...
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    14. Fabrication of thin and flexible PDMS membranes for biomechanical test applications

      For continuous analysis of mechanical properties of soft biological tissues during mechanical stimulation we developed a bioreactor to apply controlled periodic deflection to a probe. The probe attached on an elastic membrane produces a counterpressure if a certain gas volume is applied to the pressure chamber under the membrane. The related counterpressure-volume relationship describes the mechanical properties of the membrane-probe combination. To improve the signal-to-noise ratio of measurements the use ...
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    15. 1-15 of 18 1 2 »
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  2. About University of Freiburg

    University of Freiburg

    University of Freiburg was founded 1457 is one of the oldest universities in Germany, it has a long tradition of teaching the humanities, social sciences and natural sciences. The university is one of Germany's most prestigious and a leading research and teaching institution in Europe. The University of Freiburg was designated a German "University of Excellence" in 2007. Institute of Microsystem Technology (IMTEK) at the University of Freiburg is unique in Europe. The scientific scope of the institute, with 18 faculty and over 200 research and technical staff, encompasses nearly all technical fields relevant to the highly interdisciplinary world of microsystem technology. Through the depth and range of our activities, we are one of the internationally leading academic research departments in this dynamic and innovative field.